• Title/Summary/Keyword: Refining

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A Study on Refining and Melting of V by Electron Beam Melting (전자선 용해법에 의한 V의 정련 및 용해에 관한 연구)

  • Kim, Hwi-Joon;Baik, Hong-Koo;Yun, Woo-Young;Lee, Zin-Hyoung;Kang, Choon-Sik
    • Journal of Korea Foundry Society
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    • v.15 no.3
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    • pp.235-241
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    • 1995

  • In order to improve the production process of low cost and high purity Vanadium, this study was done to reduce $V_2O_5$ into V-Al master alloy by Aluminothermic Reduction, followed by refining of V-Al master alloy electron beam melting. As melting time was increased in electron beam melting of V, the contents of interstitial impurities and Al, Fe were decreased but the contents of Si, Mo and W were increased due to lower vapor pressure of these elements than that of matrix V. Consequently, it was profitable that melting of V was done for 180 seconds. In addition, with number of melting, the purity of V did not significantly vary, because volatile impurities in V were removed mostly during the first step of melting. As a result of V refining by electron beam melting, high purity Vanadium of 3N(99.91wt%) was acquired including interstitial impurities total contents of which were maximum 400ppm.

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On the High Yield Pulping of Fir by Pressurized Refining (가압(加壓)리화이닝법(法)에 의한 젓나무의 고수율(高收率)펄프 제조(製造)에 관한 연구(研究))

  • Cho, Nam Seok;Jo, Byoung Muk
    • Journal of Korean Society of Forest Science
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    • v.53 no.1
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    • pp.44-55
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    • 1981

  • Neutral sulfite precooked fir chips were refined in the Asplund Laboratory Defibrator at various temperature ($20^{\circ}C$, $120^{\circ}C$ and $180^{\circ}C$). The effects of refining temperatures on the physical property and morphological structure of the resulting pulps were discussed. Yields of precooked chips (84%, 92% and 100%) and refining temperature affected remarkably the yield of refined pulp, its beatability, sheet strength and morhphological characteristics. Pulp yield and beatability decreased with increasing refining temperature. Fiber surface of unbeaten pulp from precooked chips of 84% yield was to some extent covered by the secondary wall, while that of the pulp form precooked yield of 92% by the compound middle lamella. In the case of uncooked chips, fibers were damaged heavily, and the exposed fiber surface resulted from the equal amount of the secondary wall and the compound middle lamella. In the case of pulps prepared from precooked chips of higher yields (92% and 100%), sheet strength increased linearly as sheet density increased. But at the same sheet density, pulp from lower precooked yield (84%) had better sheet strength after open discharge refining as compared to pressurized refining, because pulp from the former had much amounts of fines fraction of higher water retention value than the latters. And there was observed a little difference in fiber length distribution but nearly similar in its morphology with increasing refining temperature.

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